This invention relates to a magnetic core for use in a wound-core electrically-inductive component, and more particularly to a gapped magnetic annulus having a magnetic metal ribbon shunt in the gap.
Annular cores are often used in inductors to provide a high inductance in a physically small inductor. When the inductive component is to be excited by a large or unsymmetrical current, or a DC excitation is to be used, then the annular core is often gapped to prevent premature core saturation of latching up. Such a gapped core may result in a compromised but still high ratio of inductance to physical size.
However, there are two distinct mechanisms that can detract from the desirability of employing gapped annular cores. One consists in fringing magnetic fluxes radiating from a core gap which may induce unwanted voltages in adjacent components or circuits, causing what is more generally called electromagnetic interference (EMI). The other mechanism is evident when an inductance having a gapped core that generally exhibits a high quality factor (Q) over a broad range of frequencies, is excited by pulses of high current, and high frequency oscillations occur which exacerbate EMI radiation.
A toroidal core comprised of annular iron laminations stacked with a gapped ferrite annulus has been taught to provide relatively EMI-free performance as a filter component in a silicon control rectifier AC power controller circuit.
It is an object of the present invention to provide an improved low cost gapped core for an inductive component producing a minimum of EMI.
It is a further object of the present invention to provide such a core being composed substantially of a relatively low cost ferrite material and only a small amount of magnetic metal.
It is more particularly an object of the present invention to provide such a core for use in a high performance switching voltage-regulator circuit.